Field of the Invention
The invention lies in the integrated technology field and relates, more specifically, to an integrated circuit configuration which, in particular, can be implemented by using copper as conductive material.
New materials are increasingly being sought for future use in integrated circuit configurations. Among others, copper is being investigated as conductive material.
In these new materials, one of the problems which arises is that semiconductor wafers, in particular silicon wafers, are contaminated by this material.
It has therefore been proposed (see, for example, M. Woo et al., 1998 Symp. VLSI Technology Digest of Technical Papers, pages 12–13, or L. Su et al., 1998 Symp. VLSI Technology Digest of Technical Papers, pages 18–19), in integrated circuits which contain copper as conductive material, to provide an insulating diffusion barrier between such conductive structures made of copper and the semiconductor substrate and, in the region of contacts of the conductive structure, to provide a conductive barrier to the semiconductor substrate. The intention of these barriers is to prevent diffusion of the contaminating conductive material from the conductive structure to the semiconductor substrate.
Furthermore, it has been proposed to provide diffusion barriers above such conductive copper structures. The barriers are to prevent the diffusion of copper into dielectric layers which are used as so-called intermetallic dielectric between different metallization planes.
In order to produce an integrated circuit having two planes of conductive structures made of copper, it has become known (see for example M. Woo et al., 1998 Symp. VLSI Technology Digest of Technical Papers, pages 12–13 or L. Su et al., 1998 Symp. VLSI Technology Digest of Technical Papers, pages 18–19) firstly to form the lower plane of conductive structures from copper. This lower plane is separated from the semiconductor substrate by diffusion barrier layers, conductive diffusion barriers being used in the region of contacts. An insulating diffusion barrier layer is applied to the entire area of the lower metallization plane, and a further dielectric layer, in which contact holes to the conductive structures of the lower metallization plane are opened, is applied to the insulating diffusion barrier layer. Then, firstly an electrically conductive barrier is applied and then the contact holes are filled with copper.
It has been shown that, even in that structure, contamination of the dielectric layer by copper occurs.